(i) Field of the Invention
The present invention relates to an apparatus for automatically delivering glass sheets for prepared slides one by one.
(ii) Description of the Related Art
FIG. 9 shows an apparatus for automatically delivering glass sheets for prepared slides suggested by the present applicant in Japanese Utility Model Laid-open Publication No. 5-61143(JU-A-05-61143).
In FIG. 9, a rack 10 for receiving a plurality of laminated glass sheets for thin type prepared slides (hereinafter merely referred to as "glass sheets") is mounted on a body 8, and glass sheets 12 at the lowest stage are successively delivered by the body 8. More specifically, when the rack 10 is set onto the mounting surface of the body 8, the upper portion of a roller 15 protrudes into an opening 10A formed in the lower surface plate of the rack 10, and as a result, the lowest glass sheet 12 is pushed up. In this state, the roller 15 is rotated, whereby the glass sheet 12 is forwardly fed through an ejection opening 14. In this state, the glass sheet 12 is also forwardly urged against the rack 10 itself, but the movement of the glass sheet 12 is restrained by means of a stopper 9. The reason why the glass sheets are obliquely maintained is that the contact pressure of the roller 15 is increased so as to readily eject the lowest glass sheet through the ejection opening 14.
When the glass sheet 12 is fed into a passage 16, its leading edge pushes down (or pushes up) a plate spring type switch 18 which extends into the passage 16, with the result that a motor 20 stops and the rotation of the roller 15 stops. When the delivered glass sheet 12 is manually pulled out, the switch 18 returns to its original state, so that the next lowest glass sheet 12 is automatically delivered.
FIGS. 10 and 11 show an apparatus for automatically delivering glass sheets for prepared slides suggested by the present applicant in Japanese Utility Model Laid-open Publication No. 6-20348(JU-A-06-20348). In the apparatus shown in FIG. 9, when the lowest glass sheet is separated from the remaining sheets, sliding resistance between the glass surfaces is so large that the smooth separation is difficult. The apparatus shown in FIGS. 10 and 11 intends to overcome this problem and is characterized in that the glass sheets are vibrated to momentarily reduce load, thereby relieving the sliding resistance between the glass sheets.
In FIG. 10, the lower surface plate of the rack 10 is formed with two openings 10A and 10B, and a rectangular roller 22 and a circular roller 24 protrude into the respective openings and come in contact with the lower surface of the lowest glass sheet 12. In this state, when the two rollers 22 and 24 are rotated, the glass sheet 12 is forwardly fed out. At that time, since the roller 22 is not circular, the rear portion of the glass sheet 12 is moved up and down, whereby the separation of the glass sheet 12 can be facilitated.
In the apparatus shown in FIG. 11, a belt 26 is passed over two rollers 28 and 30, and the belt 26 is provided on the belt surface thereof with a protrusion 31. While vibration is imparted to the glass sheet 12 with the aid of the protrusion 31, the lower surface of the glass sheet is rubbed and fed. It can be contrived that the protruding length of the protrusion 31 is adjusted to the thickness of the glass sheet and the side of the protrusion 31 is hooked on the trailing edge of the lowest glass sheet to push the glass sheet from the rear edge. However, it is difficult to hook the single thin glass sheet alone from the remaining glass sheets.
In the above-mentioned conventional apparatuses, there is a problem that in the stopped state after the lowest glass sheet has been fed out, the next lowest glass sheet partially receives the load of the remaining glass sheets, so that a large force is required to pull out the lowest glass sheet and the removal of the glass sheet cannot be smoothly accomplished.
In the apparatus shown in FIG. 9, at a time when the trailing edge of the glass sheet 12 has passed the apex of the roller 15, the delivery of the glass sheet stops, with the result that the glass sheet 12 also stops (see FIG. 9). However, about a half of the upper surface of the glass sheet 12 is laid under the remaining glass sheets. That is to say, in a range 100 of from A to B in FIG. 9, the load and the sliding resistance are applied to the glass sheet 12, so that it is difficult to manually pull out the glass sheet 12.
This fact is similarly observed in the apparatuses shown in FIGS. 10 and 11. The range of from A to B in FIG. 10 and the range of from A to B in FIG. 11 are laid under the remaining glass sheets, and so resistance to the pulling-out of the glass sheet 12 is generated. Since the glass sheets for the prepared slides are extremely thin, an excessive force cannot be applied thereto, when both the sides of each glass sheet are held to take out the same. Thus, an apparatus capable of taking out the glass sheet by merely lightly holding it has been desired.
On the other hand, in the above-mentioned apparatuses, a mechanism for pushing down the plate spring type switch 18 by the leading edge of the glass sheet 12 is employed, and therefore in order to securely push down the switch, a predetermined delivering force or more is necessary.
However, in the above-mentioned apparatuses, frictional force on the surface of the roller or the upper surface of the protrusion is utilized to deliver the glass sheet. Therefore, in the case that the returning force of the switch is large, there is a problem that the switch cannot be securely operated. If the trailing edge of the glass sheet is pushed from its rear, the delivering force can be directly transmitted to the glass sheet, but it is difficult to hook the trailing edge alone of the lowest glass sheet in the state where the glass sheets are laminated, as described above.